399 Fremont Street, Residential skyscraper in Rincon Hill, San Francisco, United States

399 Fremont Street is a residential skyscraper in San Francisco with 42 floors and a glass-and-aluminum exterior that reflects light across the neighborhood. The tower contains residential units with contemporary design and sits in a connected urban area.

The building was planned in 2006 and completed in 2016, marking a period when Rincon Hill transformed from an industrial area into a modern residential neighborhood. This development was part of a larger renewal of the area with new towers.

The tower's name changed twice before construction: Fifield marketed it as The Californian on Rincon Hill, renamed it Echelon on Rincon Hill in 2009, and it opened in 2016 under its street address. The 25,000 sq ft of shared amenity space, including a lap pool and media lounge, serves the 447 apartments as a private residents' club rather than a public venue.

The tower is a private residential building owned and managed by UDR, so its lap pool, fitness center and media lounge are reserved for residents and their guests. The site occupies the block at 399 Fremont Street in Rincon Hill, and the 238 parking spaces approved in 2009 are in underground levels. Visitors cannot tour the building.

The tower's height of 122 m (400 ft) is measured to the roof line and excludes the mechanical screening structures on top, so the structure rises somewhat higher than its official figure. The parcel of land alone cost US$52.2 million, and the project was developed as a US$317 million joint venture between UDR (51 percent) and MetLife (49 percent).